Love the name "Trapdoor".

There is no entertainers one set pay amount to give her. You should first look into what you are already making. If she gives you a fee for herself, agree with if only if there is a profit for you in a month. If there is no profit, just give her a percentage of the shows she got you.

If you already receive a lot of business on your own, raise your prices for the shows she get you. Imagine you make $500 at an adult show on weekends, performing those a lot. If she gets you shows on weekends for the same amount, you will be loosing money. But if you do few adults shows for $500 in a month, you will need her to increase your business. It all depends on what she is charging you, how much you charge personally, and how many shows you perform. Add it all together and figure out how your monthly profit with her.

But me personally will start off the first month going by commission only with her. If she does good, next add a salary too for her.

I would give it more time than just a month. Even the best managers won't make that great of progress and success in a month. Those that work the best for you are those that have a personal interest in you (and your success). Remember, it's a process. If she is interested and you feel good about her, and you trust her, sit down together, determine some agreed upon goals, direction and foundation to make sure you're both on the same page, and give her a chance. I would always work a percentage arrangement. I wouldn't raise prices just because of a manager, unless you are worth that price, and if so why haven't you already done it? At this point it isn't about the price, as much as it is about her trying it and proving herself. It's an arrangement that will always be a work in progress until it becomes automatic. Remember, initially you must help her if she is not an experienced entertainment or theatrical manager.

It can work out if you're willing to put the time, effort and understanding into it. I work with many celebrities and you would be surprised how many of them have their spouses, parents or even grown kids as their manager. Immediate ones that come to mind are Jessica and Ashley Simpson (dad), Beyonce (dad), Ozzy Osbourne (wife), Danny Bonaduce (ex-wife and now current new wife), Craig Karges (wife), Beach Boys (dad), Jackson 5 (dad), and so on, for decades, so it can work.

I think last post from Mindpro is correct, I would reinforce the idea of having a % at the beginning so your cost is Only variable, to pay a salary is to increase your overhead and your direct cost, which unless the revenue base increases to a given level because of her work, your bottom line will diminishes.

Let us know what you decided

Not too many good managers are going to do a strict percentage guys.

She's not a good manager, yet.

You could be right Danny a manager will want a salary arragement, however the need that Shawn described for a manager is revenue opportunity not management of current business or improvement of the bottom line, hence my suggestion of a fee or % of revenue, so if Shawn can make this a variable arragement even with a larger than usual fee at the beginning would be beneficial for him and the manager.
After a set and agreed time and based on the results, they can go to a lesser fee and a salary.

Also re-reading the requirement again I am not sure the role needed is a manager, which I percived as somebody more hands on the business across, here the need is lost of revenue opportunity, so you do need a sales woman more than somebody administrating the business. Maybe the discussiin should be based on needs and roles rather than in title, that will help with the compensation arragement.

Caveat: I never manage a person, always companies, so I could be missing some details in the recommendation, however at the end of the day is revenue, cost, expenses, profit, customer sat, market share and brand recognition, and each of these objectives should have somebody looking and it and how to maximize the benefit, Right?

She's not even a manager yet; do a strict percentage deal